1. Field of the Invention
The invention relates to the field of catalytic synthesis and nano-material, and more particularly to a cobalt-based nano catalyst for Fischer-Tropsch synthesis and a preparation method thereof.
2. Description of the Related Art
Fischer-Tropsch synthesis is a chemical process involving a variety of chemical reactions in the presence of catalysts to produce hydrocarbons from syngas (CO+H2). The products are mainly heavy hydrocarbons (C5+) having a relatively high carbon number, which are clean motor fuel almost free of contamination of sulfides and nitrides.
The factors related to reaction mechanism of Fischer-Tropsch synthesis include the type, size, dispersity, and reducibility of active metal particles, channeling effect of carrier (confinement effect and shape-selective effect, etc.), and promotion effect of additives. The factors affect the reactive process, and then affect the reactivity and the type and distribution of the product. Studies have shown that the dispersity of active components, active center structure, microenvironment, location, and channeling structure of carriers have a great effect on the activity and selectivity in conversion reaction of syngas. Conventional methods for preparing a catalyst for Fischer-Tropsch synthesis have a complicated process, a low CO conversion rate, and the involved raw materials are expensive. The resulting catalyst has a single metal component, the active center thereof is easy to agglomerate and thus inactive. The reaction products are mainly light hydrocarbons with high methane selectivity.
Microcapsular reactor is a new concept in nano-assembly and catalysis in recent years, which addresses the problem in traditional catalyst of being difficult to recycle as well as poor stability and selectivity. In this reactor, not only guest molecules can selectively enter the capsular space to react with reactive species in the capsule, but also its products can selectively disperse out of the reactor.